In 2006, the International Maritime Organization (IMO) updated various fire protection requirements for ships including a clarification of the requirements for monitoring and actuating the extinguishing systems if the extinguishing systems are placed inside the compartment (e.g., an engine room) that is being protected from fire.
Traditionally, these systems have been released either through mechanical pull-cables or by pneumatic means. The use of electric release was not prohibited, although no electrical equivalent to the pneumatic methods was available. The concept of a suitable electrical method that would satisfy the technical requirements of the IMO and other maritime authorities may be desirable because the installation of electrical cable on ships is expected to be less costly than mechanical or pneumatic methods.
As an example of one regulatory authority, the United States Coast Guard (USCG) originally required all firefighting systems placed outside a space to be protected in order to insure access to the release methods and to insure the system is not damaged by being in the space. Eventually, the USCG allowed some systems to be placed in the space using dual circuit pneumatic release methods but, on further evaluation, it was found that the equipment experienced significant failure. In consequence, the practice of placing fire protection equipment inside the protected space is typically considered unreliable and thus the practice of allowing the fire equipment to be placed in the fire area was discontinued. Allowing the marine authorities to return to fire equipment placed inside the protected space would require overcoming their concerns for the robustness of the equipment and the actuation methods.
For the foregoing reasons, there is a need for an electrical release for a fire protection system. The dual circuit release described herein will allow more robust equipment that will survive fire and damage. This method provides not only duplicated release but also provides supervision to annunciate or otherwise indicate a potential loss of capability before the loss of capability happens. The proposed dual circuit release will provide the opportunity to detect and correct faults to ensure the on-going robustness of the system.